Telephone system



April 1937- G. c. HARTLEY ET AL 2,076,234

TELEPHONE SYS TEM Filed Feb. 28, 1935 5 Sheets-Sheet l 1 FIG. .2

Y a. c. HARTLEY 'WENTORS nu REYNOLDS ATTORNEL J9 57' :4 W F I I 877 L191 6C2 rm: l w

April 6, 1937.

G. c. HARTLEY ET AL 2,076,234

TELEPHONE SYSTEM Filed Feb. 28, 1955 FIG. 4

S sheetsvsheet 2 lNl/ENTORS G LEY nu. REYNOLDS ATTORNEY April 6, 1937. G. c. HARTLEY ET AL 2,076,234

TELEPHONE SYSTEM k Filed Feb. 28, 1935 5 Sheets-Sheet 3 :5 V6 mm: FIG. 5 H EY-M-RL L v JZV- L -0 R5! 1 x HH5 J! k I i 2 JR: ax; ERL g I RING I a v -i-i Q I' :5 I Q -2 t I RS4 Hh'o' J2 zg l I S L F c: i h

5 RR 7 RBXISTL/NE RING/N6 AND C ODE CIRCUIT S m PULSES RING.

' G.CHAR7ZEV H. JREVNOLDS ATTORNEY Patented Apr. 6, 1937 UNITED STATES PATENT OFFICE TELEPHONE SYSTEM Application February 28, 1935, Serial No. 8,606 In South Africa March 29, 1934 15 Claims.

This invention relates to automatic or semiautomatic telephone or like exchange systems comprising multi-party subscribers lines, commonly known as party lines.

Areas are known in which the exchanges are of the central battery type, so that the subscribers telephone sets are normally Without local batterysupply, but in which on some multiparty lines, for instance, the subscribers sets are provided with local batteries for talking current purposes.

The local-battery subsets are usually arranged for dialing and signaling over circuits between the subsets and the exchange different in type from the dialing and signaling circuits used be tween central-battery subsets and the exchange.

The type of circuit used for dialing and signaling between a central-battery subset and the exchange to which it is connected in this country and many other countries is what is known as a loop circuit in which a direct current connection is completed between the two wires or legs of a subscribers line through the subset when the switch-hook is raised, and current is fed round the loop so formed from a battery con nection to one leg and an earth connection to the. other leg of the line at the exchange.

The'type of circuit largely in use for dialing and signaling between a local-battery subset and the exchange to which it is connected is what is known as a simplex circuit; the current supply for this circuit is at the exchange, although a local battery is supplied for talking purposes, and current is fed over the two legs of the subs'cribers lines in parallel from battery connections to both legs at the exchange to an earth connection to each leg at the subset When the switch-hook is raised. This type of dialing circuit can be used for long lines, and is particularly applicable to multi-party line working since it is not seriously aiiected by the bell condensers of the parties subsets.

One object of the invention is to provide means whereby calls from subscribers lines arranged for different types of signaling can be efficiently and economically dealt with by automatic equipment.

Another object of the invention is to provide improved revertive call arrangements for exchanges comprising party lines, revertive calls being calls between two subscribers on the same party line, whereby no exchange equipment associated in common with a number of subscribers lines is held in use during such calls.

Another object of the invention is to provide novel means for controlling code ringing in sys-- tems using single-motion conversation switches which are set by control switches.

Another object is to improve the pulsing circuit arrangements for controlling the establishing of connections.

One feature of the invention comprises an automatic or semi-automatic central-battery telephone or like exchange system comprising multi-party lines and single-party lines, on some of which the subsets are arranged for signaling between the subsets and the exchange over one type of circuit, and on others of which the subsets are arranged for signaling between the subsets and the exchange over a different type of circuit, and comprising exchange equipment which is associated in common with subscribers lines requiring both types of signaling circuit, and which includes discriminating means adapted to determine the type of signaling circuit required for a subscribers line temporarily connected thereto in setting up a connection, current feed equipment, and switching means controlled by the discriminating means for modifying the circuits of the current feed equipment temporarily connected to a subscribers line.

Another feature comprises an automatic or semi-automatic central battery telephone or like exchange system comprising multi-party lines, in which, in a revertive party line call, automatic exchange equipment seizes the busy calling party line, determines that the call is revertive by the simultaneous freeing of both ends of the connection when the calling party hangs up in response to busy tone, and rings the wanted party, and in which, on the reply of the wanted party, the exchange equipment other than that individual to the party line is released.

Another feature of the invention comprises an automatic or semi-automatic central battery telephone or like exchange system comprising multi-party lines, single-motion connector switches, and single-motion digit responsive control switches which are associated with said connector switches and which act both as marker switches for controlling the setting of associated connector switches and as code-ringing control switches.

Another feature is a pulsing circuit in which impulses may be repeated satisfactorily, for the proper control over the establishing of connections, from a pulsing relay that may vary its make and break periods within a wide range of percentages.

The invention will be clearly understood from the following description of one embodiment of the invention which is shown in the accompanying drawings, in which Fig. 1 shows the line circuit of a single-party line without local battery and adapted for loop circuit signaling.

Fig. 2 shows the line circuit of a 10-party line without local batteries and adapted for loop circuit signaling.

Fig. 3 shows the line circuit of a -party line with local batteries and adapted for simplex circuit signaling.

Figs. 4 and 5 show a link circuit of a rural exchange comprising a 10-level 51-point single- 5 motion finder switch F giving access by means of staggered wipers to a maximum of one hundred lines, and a IO-level 51-point single-motion contor switch S having two separate sets of wipers and giving access by means of wiper-switching 0 arrangements to a maximum of one hundred junctions and subscribers lines.

The link circuit also comprises a -point single-motion control switch D which uses the first ten points for receiving the first digit dialed,

25 for operating discriminating relays in accordance with the value of the first digit, and for marking the groups of outlets in the bank of switch S, The remaining contacts are used for receiving one or two ringing code digits for calls 0 to party lines. The ringing codes are determined by wipers D. R. 2 and D. R. l. The bank contacts in level D. R. 2 are each connected to multipled ringing code control contacts on different levels of a ringing code switch in a common ringing and pulse circuit. Lead SRL is multipled to a ringing code switch level giving a standard ringing code for calls to single-party lines, while leads CRL are each multipled to a different level of the ringing code switch giving a different ringing code. The leads CRL control ten codes while connections between corresponding contacts in bank D. R. l .and ringing code switch act to modify the ten ringing codes via D. R. 2 alone to give a further ten ringing codes. The circuits in the right-hand bottom corner are for signaling to the common ringing and pulse circuit for various purposes. The chain dotted figures G-FE and DFE show the current feed equipment to the calling and called lines respectively. The circuits of these equipments are normally arranged for loop signaling but either can be modified to provide a simplex signaling circuit by relay SI or relay DX respectively. Relay SI is operated via wiper F. D. if a calling line requires simplex signaling while DX is operated via wiper S. Di or S. D2 if a called line requires simplex signaling.

Detailed description will now be given of the embodiment shown in Figs. 2, 3, 4 and 5 of the drawings.

When the subscriber lifts his receiver the line relay L operates in one of the following circuits:-

For CB circuits from battery, relay L, Figs. 1 and 2 KI, subscribers loop, K2, earth.

For simplex circuits from battery, relay L, Fig. 3 KI to earth at the subscribers station.

L operates SA Fig. 4 (battery, SA, K3, Li, earth) .and connects battery via low resistance right-hand winding of K, Figs. 1, 2 and 3, K4 to the H banks of the F switches Fig, 4 to mark the calling line. SA connects earth toa free link via the start chain, which distributes calls. ST in the link Figs. 4 and 5 operates (battery magnet DM, and interrupter springs, switch D,

H wiper and home contact, switch S, wiper D2 and home contact, relay ST, BB2, start chain, SAI, earth) ST operates relay B and drives the F switch in search of the calling line (battery, magnet FM, and interrupter springs, STI, LI-II, Pl, H5, JM3, ST2, earth). B is pre-energized by ST in order to reduce the seizing time of the circuit. When F reaches the calling line, P operates (low resistance battery in line circuit, F. H. wiper, ST3, relay P, earth), opens the F driving circuit at Pi and locks (battery, resistance YL, STE, relay P, Pl, H6, JM3, ST2, earth). At P2 earth is connected via S'I'3 to the line circuit H lead which makes the line busy on the S switch multiple. Relay K Figs. 1, 2 or 3 in the line circuit operates in series with a holding winding of L to the same earth and at KI and K2 disconnects the line circuit feed from the subscribers line. L now holds in series with K. P also operates LH (battery, YM, relay LH, ST4, Pl, Ht, JM3, ST2, earth). LH locks via BI to LH5, and at LHZ, Ll-I3 connects the subscribers line through to the AS relay via F-land F wipers and banks. The link now discriminates as to whether the call is from a simplex line, an ordinary CB line, or a long single-party CB line This is performed by means of the D bank of the switch F. Relay SI is multipled to contacts in bank D of F corresponding to simplex lines, LL is multipled to contacts corresponding to long C. B. lines, and R to contacts corresponding to coin box lines.

If the line is a simplex one relay SI operates via this bank and connects: center point battery to the subscribers line. This circuit may be traced from battery, lower windings of relays AS and TC, TCZ or resistance YH, SII, upper windings of AS and TC, TCI or resistance YV, SI2, via SD windings in parallel to the positive line via the upper winding of SD, and via the lower winding of SD and SIS to the negative line. AS operates to the center point earth in the subscribers set. In neither case is there any current flow to the relay A as this is opposed by rectifier MRA.

In the case of a CB subscriber SI does not operate and the subscribers talking feed is supplied from battery via lower windings of AS; TC, at SI3, to the negative line and from earth via S12, upper windings of TC and AS and SH to the positive line.

In the case of long single-party lines, relay or impedance LL is energized via the D bank and modifies the magnetic field of the impulsing relay AS. LL is mounted adjacent to AS and by setting 11p: an external magnetic field assists the impulsing on these long lines.

Relay TC is marginal and operates on lines having less than -ohms resistance. At TCI and T02 it introduces additional resistance into the feed in order to reduce the transmitter current on these short lines.

Relay AS operates relay A via AAI, ASI and A operates BB and AA in obvious circuits. Relay BB locks via LH? to BB3 and the same earth from BB3 is extended via A i to hold B when ST subsequently releases.

Relay K releases relay SA unless another line is calling, and SA releases ST. ST is slow to release in order to allow time for the operation of LH, AS, A and BB. If SA is held by another calling line, BB releases ST at BB2. Contacts LH5 maintain earth on the H lead when ST3 opens. ST releases P at ST5 and ST4 and opens the original driving circuit for F. BBI now supplies the common earth for the circuit in place of STZ, and this earth is extended via JM3, HH4, BB6 and switch D.C wiper and home contact to the dial tone start lead DTS. Dial tone is connected via lead DT, switch D. R2 wiper and S.TI wiper, J4, CO3, H5, condenser QG, XG4, QD to the negative line. When AA operates A is held via resistance YU, AI and ASI. The link is now held by the calling subscriber and is ready to receive impulsing.

Failure to dial While the circuit is waiting for impulsing to commence battery is connected via resistance YN, H4, LHE, relay ZA, 2A3, to lead TA to start the time pulse-machine and thus connect a tuned A pulse to the lead TA. This lead is connected to a high resistance time pulse start relay (not shown) and ZA does not operate. When the A pulse condition is given the high resistance winding is replaced by a low resistance winding and ZA operates. ZA locks via the hold lead HL, prepares a circuit for forced release of the link circuit and holes the time pulse start relay via the hold lead HL. After a predetermined period of about half a minute earth is connected to the Z pulse lead ZL, and if ZA is still up, that is if the subscriber has failed to dial, LH is short-circuited and releases. LH releases AS at LHZ and LH3, and ZA at LE6. LE4 removes earth from the H lead, which releases relay L. During the release of L, K remains held via its left-hand winding and its high resistance middle winding in series with resistance YA, K3 and LI. When L has released, K is connected to the subscribers line and remains held to the calling condition. In the CB circuits, Figs. 1 and 2, K is held via its left-hand and middle windings, L2, Kl, subscribers loop, L4 to earth; in the LB. circuit, Fig. 3, K is held via its left-hand and middle windings, L2, Kl, to earth at the subscribers station. The line circuit remains locked in this condition until the RG. is cleared. On release of AS in the link circuit A releases followed by AA and B; B releases BB and link circuit returns to normal.

First digit received The subscriber dials the first digit, relay AS responds to the openings in the subscribers subset circuit and steps switch D by means of the impulse correcting relays A and AA as follows.

On release of AS, A releases followed by AA which releases slowly due to the rectifier RR. On release of AA, A can now reoperate, if AS has reoperated, via AAI, ASI. In the case of a short break if AS reoperates very quickly A is prevented by AA from reoperating too soon. At the end of the first impulse, when AA is back A operates and locks to earth via AA2 A2. AS has a locking circuit for its lower winding via rectifier MRA, Al, resistance YU, AAI, ASI to earth. This circuit ensures the reception of a very short make, sufiicient only to operate the light contact ASI. AA reoperates and if AS is still up A holds via Al. At the beginning of the second impulse AS releases releasing A and the cycle is repeated. On the first release of A switch D is energized and relay C operates (battery, switch magnet DM, EI, G2, EH3, relay C, A5, BB4) C operates CC via Ci to the common ground BBI. When A reoperates D steps to the first contact disconnecting leads DTS, DT. The interaction of relays A and AA is such that the impulses given to the D switch and.- B relay via A are approximately 50 per cent make and break for a wide range of make and break percentage on the ASI contact. Satisfactory impulsing is obtained although the line conditions may give make or break percentage on AS of over per cent.

A opens the circuit B at A4, but B is slow to release and holds during impulsing. C also holds during impulsing. On the first step of D, M operates (battery, resistance YS, relay M, V2, S. C wiper and bank, D.C wiper and bank, BB6, HH4,. JM3, to the common ground). D continues stepping until the end of the digit. 0n the third step (if three or over is dialed) M releases and earth is connected via D.Rl bank and wiper, BB1, S.N bank, home contact and wiper, E1, S interrupters to the magnet SM) S steps off normal and drives until it reaches the beginning of the group indicated by the position of D. The driving circuit for S is' via the off normal are N, G4, Vi, Ml, LHI, PI, 1-16 to the common ground. M then operates via wipers S.C and D.C and the marking connections and at MI opens the driving circuit for S. Contacts l, 2 of wiper D.C are connected to contact I of wiper SC, contacts 3, 4 of wiper D.C are connected to contact II of wiper S. C and so on. If switch S reaches its contacts H while D is still on its contacts 3 or 4, M operates and stops S; if D then steps to contacts 5, S steps on to contacts 2| unless or until D steps to contacts I, and so on. In this way the position of S is controlled by relay M dependent on the position reached by D. At the end of the digit contacts A5 remain open and C releases followed by CC. If S has now reached the contact marked by D, or when it does so, M operates and earth is connected from the common ground via H6, Pl, LHI, MI, 0C2, E2, to the D wiper of switch D. This operates discriminating relays which control the subsequent operation of the call.

If the digit dialed is even. (2, 4, 6 or 8) J (10- cal call) operates and locks to BB3. J operates E (battery, relay E, 0G5, J3, HH4 to common ground). If an odd digit is dialed E operates directly. If 0 is dialed indicating an outgoing call 0G operates and extends its operating earth via 0G2 to J which also operates and locks.

Local call On a local call, as described in the last paragraph, relay E is up and J is also up if the first digit is even. D is resting on the outlet corresponding to the first digit and switch S is held under control of M on the outlet preceding the tens group required. Relays AS, A, AA, B, BB, LI-I, M, and E are up and relays SI, LL, ZA and J may also be up. E locks via E5 to the common ground and drives switch D to the eleventh contact (battery, magnet DM, interrupter springs, contacts l-lll of the D. H. bank, E6).

When D drives M releases but E1 prevents the driving of S. If J is up, it switches over to the even banks of the S switch.

The circuit is now ready to receive the units digit of the subscribers number. The impulsing circuit operates as described previously but since contacts El are operated, the impulsing circuit comprises magnet SM instead of DM and switch S is stepped. The units digit might equally well be received by switch D, the switch S being set to the wanted line under control of D. C and CC operate as before and S reaches the required subscribers line. At the end of the digit C releases and at Cl removes earth from the CC winding.

CC now holds via CCI, E2, D.D wiper in series with relay G, FI, DD4 to the common ground, and G can now operate due to the removal of the short circuiting earth at C1. G locks on its second winding via GI and subsequent operation depends upon Whether the called line is a PBX. line, party line, or regular line. The discrimination is determined by bank SD! or S.D2 according to the condition of contacts J5. Contacts in these banks corresponding to P.B.X. first lines are connected to relay V, contacts corresponding to C.B.l-party lines to relay X, and contacts corresponding to LB simplex ZO-party lines to relay DX. 5

Call to a single-party regular line G operates FF (battery, relayFF, F2, G3 to common ground) and J M. JM releases E at JM3. On the release of E, P is connected to the test lead of the called line (earth, P relay, JMZ, E8, 003, J4 to test bank Tl or T2 of S). CC is released by E2 but due to the shunt YT, releases slowly and during its release P tests whether the line is free. On release of E, XG operates (battery, XG Winding, E l, G6, rectifier MRB, LI-I5, earth) to indicate end of selection. The impulsing and drive circuits are open at G4 and G2 when E releases. If the line is free, P operates in series with the low resistance ri ht-hand winding of K in the line circuit P short circuits its loo-ohm winding at P2 to busy the line, as described previously, and locks on its 20-ohm winding (battery, resistance YK, H2, G7, relay P, Pl, H6 to common ground). L and K operate in series in the line circuit on their right and lefthand windings respectively and relay H operates in series with P in the link circuit. H looks at HI and operates HH at H2. H6 releases P and H3 maintains earth on the test lead of the line circuit. HH switches the transmission circuit through to the subscribers line at HHE and HHS. The ring start circuit is energized by battery via H4, XG2, relay RS and lead RSL. ZA is released if up. When the ring start pulse arrives, low resistance earth is connected to the ring start lead RSL and RS operates. RS locks (battery, RS left-hand winding, RS2, Gl, Fl, DD l to common ground) and connects a winding of relay R via RS6 and DB2 bank to the standard ringing lead SRL on the ringing code switch (not shown) in the ringing circuit. As the ringing code switch steps earth at the standard ringing period is connected to DRZ bank and R responds. R connects ringing via lead RL, RI, RSI, HH5 and J l to the subscribers line returning via J2, HHG, RS4, DXS to earth on lead ERL. At each release of R relay F is connected at R! to the subscribers line and tests whether he has replied. Ringing tone is connected via lead RTL, condenser QH, HHI, V5, XG l, condenser QD to the calling party.

When the called subscriber replies F operates and releases FF at F2. On release of FF, G and RS release since FF! and F! are both open and RS connects DS and IS to the subscribers line. G releases XG at G6 and XG disconnects ringing tone and the ringing circuit. On release of G, H keeps the impulsing circuit open at HH3. IS and DS operate in series with the subscribers loop and IS operates DD (battery, DD winding, R2, HHZ, ISI). DD connects battery via 300- ohm resistance YF and via JMl, DDI, 0G8 to the calling subscribers meter lead and operates the subscribers meter. The meter is marginal and does not operate in series with the 2000-ohm resistance YG. JM has been holding via 0G6, DD3 and JM3 and via contacts G3. Contacts DD3 are nowopened. On release of G, JM releases slowly and disconnects battery via resistance YF from the meter lead again. Relays AS, A, AA, B, BB, H, HH, IS, DS are now up and. conversation proceeds. DD reverses the positive and negative lines at DDI DD2, DD5, DDB to give supervision to a calling operator on incoming manual calls, or for coin box signaling purposes.

When the calling party clears, AS releases followed by A, AA, and'B in turn. B releases LH; LH releases BB. Contacts LH4 disconnect earth from the finder H lead and release the calling line circuit relays. BB releases H, HH and J if up. HH releases IS, DS and DD and H releases the called partys line circuit. If the called loop is still complete, K in the line circuit remains held to it in the PG. condition.

Switches S and D drive home in the following circuitsbattery, magnet SM and interrupter springs, E'l, S wiper and bank N, BBI and battery, magnet DM and interrupter springs, D wiper H bank, E6 to BB3 at contacts H and I2, DX8, X5 and CG? at contact l3, and BB4 at contacts i l to 24. When these switches reach the home position, the start circuit via ST is complete again.

If the called party clears first, DS and IS release and IS releases DD. DS2 connects battery via H6 and XG2 to the ZA relay. The time pulse start lead is energized and when the A pulse arrives ZA operates, locks and prepares a forced release circuit for LH. If the calling party continues to hold the link circuit, LH is released when the Z pulse arrives and releases the link circuit. AS, A, AA, B and BB release and BB releases the other held relays. The calling line circuit locks to the PG. condition, as described previously, and called line circuit is released at H3.

If the called line is busy, P fails to operate before the release of CC. At CO3 the testing circuit is disconnected. XG operates, as described previously, and busy tone is connected to the calling line from lead BTL, via HHl, V5, XG4, condenser QD and the negative lead.

Call to P.B.X. group The S switch is positioned on the first line of the group and relays AS, A, AA, B, BB, LH, E, CC and G are up; SI or J may also be up. The first line of the PBX. group is distinguished by being connected to the V relay on the DI or D2 bank of S. When G operates, V operates via S.Dl bank, J 5, HH8, G3 to the common ground. V locks via M2 and V3. FF and JM operate, as described previously, and E releases. Until the operation of JM, M operates for a moment without efiect via V2, E5, JMS to common earth. With V up CC holds via Vi, Ml, LHI, PI, H6 to the common ground, and extends this earth via CC! and V4 to the magnet SM. S drives over the PBX. group and P tests each line via the testing circuit described previously. During this hunting for a free line in the group, V5 keeps busy tone disconnected from the line. When a free line is reached (this may, of course, be the first line) P operates and opens the driving circuit for S at Pl Pl also releases CC. H and EH operate, as described previously, and HH8 releases V. The call now proceeds normally.

If an intermediate or last line of the PBX. ls dialed, the call proceeds as for a regular line.

If all the P.B.X. lines are busy M operates when S reaches the last line of the group (battery, resistance YS, relay M, V2, P.B.X. last line on S.DI or S.D2 bank, J 5, 1-11-18, G3 to common ground). M releases V at M2 and opens the driving circuit '5 for S at MI. V releases M at V2 but VI is now back and CC continues its release. On the release of V, busy tone is connected via XG4 to the calling line. If the last line is free P operates as well as M, and the operation of M is immaterial.

Call to c. B. ZO-party line Relays AS, A, AA, B, BB, LH, E, CC and G are up; SI and J may also be up. Switch S is positioned on the called line and if it is a 10-party line X operates via the D! or D2 bank (battery, relay X, S.D2 bank and wiper, J5, HI-IB, G3 to common ground). X locks via XI and holds E from common earth via X4, RCI, XGS, E5 and 0G5 on the operation of JM. JM and FF operate as described previously. X now drives D from contact H to contact l3 (battery, magnet DM and interrupter springs, D. H wiper bank, X5, 0G1, to earth). With E up CC remains held in series first with relay G on contact II and then with relay X on contact l2, but releases when D steps on to contact I3. The circuit is now ready to receive the third digit. This digit indicates the party required and is received by the D switch (battery, magnet DM, X2, E3, G2, EH3, relay C, A5, BB4, earth). The position of D now indicates the ringing code required. C and CC operate during the digit and at the end of the digit C releases and at C! removes a short circuit from the XG relay. XG operates (battery, CC relay, CCI, E2, D.D wiper and bank, OGI XG relay to common ground). XG locks via XGI, G6, rectifier MRB, to LH5 and releases E at XGB. As before, XG indicates the end of selection in the 40 link. E opens the impulsing circuit at E3 and closes the line testing circuit at E8. CC releases as before and if the line is free, P and H operate during its release. HH operates and RS operates to the ringing start pulse as described previously. RS connects R to the ringing code required via the D.R2 bank. R responds to the ringing code ground and connects ringing to the line as described previously for the standard code. The operation of RS by a ringing start pulse insures that a clipped code is not connected to the called line.

If the subscribers line is busy, P and H do not operate and on the release of CC, RC operates (battery, relay RC, X3, XGES, H5, CC3, J4, S bank Tl or T2, to earth in the link which is busying the called line) RC is operated in order to prepare for revertive calling conditions, described later. XG4 connects busy tone to the calling line.

' Call to local battery ZO-party line Relays AS, A, AA, B, BB, LH, E, CC and G are up; SI and J may also be up. Switch S is resting on the called line and if it is a 20party line DX operates via the S.Dl or S.D2 bank. DX locks via DX3 and holds E from common earth via DXI, RCI, XGG, E5 and 0G5; FF and JM operate as before and the circuit is ready to receive the third digit. In this case, switch D does not drive since X is not up. The third digit is accepted by magnet DM via DXG, E3 and G2. The digit dialed will be either 1 or 2; if it is l, X operates in series with CC via contact l2 of bank D.D, when C releases at the end of a digit and removes the short circuit from the 200-ohm winding of 75 X. X locks via XI and G3, and steps D to contact l3 by connecting earth via 0G1, X5 to con tact I2 of the DH bank. If the digit dialed is 2, D is stepped to contact l3 and X does not operate. Cl releases CC. The circuit now waits for the fourth digit.

The fourth digit is accepted by D as before so that it is positioned on the required ringing code. When C releases at the end or" the digit, XG operates in series with CC as described previously. XG releases E at XGE and the line is tested. If the line is free, PH and HH operate and switch through; RS operates when the ring start pulse is received and code ringing is connected to the line by the operation of R to the ringing code pulses. If the third digit is 1, X is up and R responds to one of the ten basic ringing codes received via the DB2 bank. The other ten ringing codes which are required if the third digit is 2 are obtained by adding a pulse to each of the ten basic codes. This pulse is received by R via the DR! bank on its lower winding, X being back in this condition. Two ringing code pulse leads are shown since in one case slightly different timing is required from that of the other codes. There is no reason why these additional code'pulses should be limited to two.

Since DX is up, relay F is connected to both lines in parallel when R is deenergized so that F trips to the center point earth via both lines. With R up, however, ringing still goes out on the positive line returning via the negative line. When the subscriber replies, DS and IS both operate to the center point earth at the subscribers station, since DS is now connected to battery via DX2.

If the line is busy, E and CC release and RC operates as described for the lo-party line case.

Instead of having two ringing code digits, it would be possible to have one such digit only, if each ten subscribers on the party line were given a separate directory number. This, however, would complicate the revertive call arrangements. Alternatively, two code digits could be used for both types of party line, the first digit not having any function with regard to ringing code selection.

Release from a busy or no reply call If the called subscriber does not reply, the link releases when the calling subscriber clears. AS, A, AA and B release in turn, B releases I-IH which releases BB and BB releases the other party relays. D and S drive home and the link circuit becomes normal.

In the case of a busy call, when the subscriber clears release is similar. If, however, the subscriber continues to hold the link circuit ZA is operated by battery via LI-Iii when the A pulse arrives, and when the Z pulse arrives, LH is short-circuited and the link releases. The calling line circuit locks up in the P. G. condition.

Revertlve calls Relays AS, A, AA, B, BB, LH, G, XG, JM, FF and RC are up; SI, J, X and DX may also be up. If a revertive call is being made, the S and F switches are both positioned on the same line circuit and busy tone is being returned to the calling party. RC is held via X3 or DX4, XG3, H5, CO3, J5, S wiper Tl or T2, F wiper H to LE4. If, however, the call is to a different busy party line, F and S will not be positioned on the same line circuit.

The calling party replaces his receiver, AS releases followed by A, AA, B and LH, but since RC is up, BB remains held via RC3, BB3. LI-I releases ZA at LHB and SI if up at LH5. At LH4 earth is removed from the RH lead and RC starts releasing. However, RH is applied to the line test lead by the release of LHB before RC has time to release, the circuit extending over the closed contacts RC4. If the call is a revertive one, RH operates in series with the line circuit relays L and K, which hold. RH locks via RH2 and holds RC via G5, RH! and RC2. The holding earth of RC is extended via X3 or DX4 to the line circuit relays. LH releases XG, at LHEE, and RH operates H via RH3, BBI. H now holds the line circuit at H3. I-IH also operates via H2, RHS, BB! and reoperates XG via E4, G6, I-II-Il, RC! and DXI or X4.

RS operates to the ringing start pulse and code ringing is sent out on the line. When the called party replies ringing is tripped in the normal way; F operates and releases FF which releases G and RS; G releases KC and RC. DS and IS operate to the answering conditions and IS operates DD. DD releases JM and X if up. On release or" G earth is connected to the lead F.1VI during release of RC.

In the case of IO-party CB. lines this ground operates the transmission feed relay R in the line circuit which connects itself to the sub scribers loop, supplies transmission feed and remains held by the loop until the end of the call. The earth has no effect on a local-battery line as the meter is connected to earth. On release of RC, BB releases followed by the remaining link circuit relays. S and D drive home and the link circuit becomes normal.

The line circuit locks to the calling condition until the end of the call. When both subscribers clear the line circuit releases.

If a subscriber makes a revertive call and fails to clear after getting busy tone, the link circuit is forcibly released by the Z pulse which causes the release of LH so that the circuit goes into the revertive calling condition. Ringing is immediately tripped since the calling subscriber is on the line. The line circuit is then left in a revertive calling condition dependent on the calling loop alone.

In the case of a call to a busy party line, when the calling party clears AS, A, AA, B and LH release, and RC commences to release. Since the subscriber still remains busy, RH does not operate and at the release of RC, BB releases followed by the remaining relays. SD drives home and the link circuit becomes normal.

What is claimed is:

1. In a telephone system, an exchange, two types of subscribers lines terminating in said exchange and arranged for different types of signaling, current feed equipment at said exchange, and means responsive to a subscriber of either type of line calling the exchange for establishing a connection from said current feed equipment to the calling subscribers line to permit the particular type of signaling required for the calling line to become effective at the exchange.

2. In a telephone system, an exchange, subscribers lines adapted for simplex dialing terminating at said exchange, subscribers lines adapted for loop dialing terminating in said exchange, current feed equipment for dialing at the exchange, means for connecting a calling line to said current feed equipment for reception of dialing signals, discriminating means for determining the type of line calling and switching means controlled by said discriminating means for modifying the current feed equipment to permit the type of dialing required by the calling line.

3. In a telephone system, an exchange, subscribers lines adapted for simplex dialing and signaling, subscribers lines adapted for loop dialing and signaling, exchange equipment common to said lines for establishing connections between calling lines and called lines including discriminating means for determining the type of line calling and the type of line called, means controlled by said discriminating means for varying the exchange equipment to respond to the type of dialing transmitted by the calling line and to signal with the type of signals required by the called line.

4. In a telephone system, an exchange, subscribers lines adapted for simplex signaling current feed, subscribers lines adapted for loop signaling current feed, connector circuits each including current feed equipment and discriminating means for determining the type of current feed required for connection to and signaling over a called line, and switching means controlled by said discriminating means for modifying said equipment in accordance with the type of signaling required by the called line.

5. In a telephone system, multi-party lines, exchange equipment operative in case of a revertive call for establishing a connection from the calling line terminals to the exchange equipment and for finding the called line terminal of the same line, means responsive in said exchange equipment when the calling party replaces his receiver on the switch-hook in response to the calling line testing busy for freeing the calling line terminals from the connection and ringing the called party over the called line terminals, and means responsive to the called party answering for releasing the connection through the exchange equipment.

6. In a telephone system, party lines, connector switches, a digit responsive control switch associated with each connector switch, and means operative by said control switch in making calls from one line to another or from one party to another on the same line for marking lines to which connections are to be made over the associated connector switch and for selecting the ringing code to call the desired party on the wanted line and controlling the ringing of the desired party.

'7. In a telephone system, an exchange, short and long subscribers lines, adapted for simplex current feed, short and long subscribers lines adapted for loop signaling current feed, connector circuits each including a current feed relay and a marginal relay, two impedances and a source of current with battery normally connected to one leg of a subscribers line via one winding of the current feed relay, one winding of the marginal relay and one impedance, and ground normally connected to the other leg of the subscribers line via another winding of the current feed relay, another Winding of the marginal relay and another impedance and with the impedances normally short-circuited through contacts of the marginal relay, said marginal relay being operative only when the connector circuit is connected to short lines to include the impedances, a discriminating relay operative when the connector circuit is connected to a calling or called line adapted for simplex current feed for connecting the battery in both windings of both relays and the impedances in series connection to both legs of the connected line in simplex.

8. In a telephone system, an exchange, short and long subscribers lines, connector circuits each including a current feed relay and a marginal relay, two impedances and a source of current with battery normally connected to one leg of a subscribers line via one winding of the current feed relay, one winding of the marginal relay and one impedance, and ground normally connected to the other leg of the subscribers line via another winding of the current feed relay, another winding of the marginal relay and another impedance and with the impedances nor mally short-circuited through contacts of the marginal relay, said marginal relay being operative only when the connector circuit is connected to short lines to include the impedances.

9. In a telephone'system, an exchange, short and long subscribers lines, connector circuits each including a current feed relay and a marginal relay, two impedances and a source of. current with battery normally connected to one leg of a subscribers line via one winding of the current feed relay, one winding of the marginal re lay and one impedance, and ground normally connected to the other leg of a subscribers line via another Winding of the current feed relay, another winding of the marginal relay and another impedance and with the impedances normally short-circuited through contacts of the marginal relay, said marginal relay being operative only when the connector circuit is connected to short lines to include the impedances, another relay having an inductive winding in each connector circuit, means for operating said relay when a long} line is connected to a connector circuit, said other relay being so placed in relation to the current feed relay in the same connector circuit that its magnetic field aids the magnetic field in the current feed relay Winding.

10. In a telephone system, subscribers lines adapted for simplex signaling, subscribers lines adapted for loop signaling, a connector switch, a circuit therefor, means for connecting subscribers lines through a connector switch to its circuit, a discriminating relay associated with each subscribers line adapted for simplex signaling operative when a connector circuit is connected to a subscribers line adapted for simplex signaling, an answering test relay in said connector circuit, means for signaling a subscribers line when connected to a connector circuit, means for connecting} said answering test relay to a connected line during signaling, means for operating said answering test relay when the called subscriber answers, two battery feed relays in said connector circuit adapted to feed ground or battery via the winding of one battery feed relay and battery via the winding of the other battery feed relay, means operative when the connector circuit is connected to a subscribers line adapted for simplex signaling and the associated answering test relay is operated and the associated discriminating relay is operated for feeding battery to said line via the winding of said battery feed relays in simplex to both legs of the subscribers line, and means operative when the connector circuit is connected to a subscribers line adapted for loop signaling and the answering, test relay is operated for feeding battery to one leg of said line via the winding of one of such feed relays and ground to the other leg of said line via the winding of the other feed relay.

11. In a telephone system, common battery party lines, a line circuit for each line including a current feed relay, exchange equipment operative in case of a revertive call for establishing a, connection from the line circuit of a calling line at callingline terminals through the exchange equipment tothe called line terminals of the same line circuit, a revertive call discriminating relay in said exchange equipment, means in said exchange equipment responsive when the calling subscriber replaces his receiver on the switch-hook in response to the calling line testing busy for ringing the called party and operating said discriminating relay, means in said exchange equipment operative when the called subscriber answers the call for operating said current feed relay in the line circuit of the calling line under control of said discriminating relay and for thereafter releasing said exchange equipment, and means for maintaining said current feed relay operated as long as either partys receiver remains oil the switch-hook.

12. In a telephone system, single lines, common battery party lines, local battery simplex party lines, connector switches, a digit responsive control switch associated with each connector switch, means operative in response to the reception of a tens digit for setting a control switch to mark a corresponding group of lines, means responsive to the setting of said control switch for selecting said group of lines on the associated connector switch, means responsive to a unit digit for thereafter setting said connector switch on the terminals of the desired line, means responsive in case the desired line is a single line for testing said line, means operative in case the desired line is a party line for setting said control switch in response to a ringing code digit, and for transmitting the selected ringing code to the connected line to call the desired party, and discriminating means in said connector switch for determining whether the called line is a common battery party line or a simplex local battery party line and for causing the ringing tone to be transmitted out over the connected line in a loop circuit in case the called line is a common battery party line or in, a simplex circuit in case the called line is a local battery simplex party line.

13. In a telephone system, subscribers lines adapted for simplex signaling, subscribers lines adapted for loop signaling, connector equipment, means for connecting a calling line through said connector equipment to a called line and signaling said called line with the type of signaling required by said line, an answering test relay in said connector equipment, a current feed for said test relay, means for connecting said answering test relay to the called line intermittently between signaling periods so that the current feed is supplied to the called line in a simplex or in a loop connection as required by the type of line connected.

1%. In a telephone system, a first impulse responsive relay, a second impulse repeating relay, a third relay, an operating circuit for said second relay including operative contacts of said impulse responsive relay and normal contacts of said third relay, a locking circuit for said second relay including normal contacts of said third relay and operated contacts of said second relay, an operating circuit for said third-relay including operated contacts of said second relay and a locking circuit for said impulse responsive relay including normal contacts of said second and third relay.

15. In a telephone system, a first impulse responsive relay, a second impulse repeating relay, a. third relay, an operating circuit for said second relay including operative contacts of said impulse responsive relay and. normal contacts of said third relay, a locking circuit for said second relay including normal contacts of said third relay and operated contacts of said second relay, a holding circuit for said second relay including operated contacts of said first relay and operated contacts of said second relay, an operating circuit for said third relay including operating contacts of said second relay and a locking circuit for said impulse responsive relay including normal contacts of said second and third relays.

GEORGE CLIFFORD HARTLEY.

WILLIAM JOHN REYNOLDS. 

